Abstract[unreadable] Arrhythmias are a major cause of morbidity and mortality, with more than 250,000 people dying[unreadable] suddenly each year in the United States. Most arrhythmias are acquired and result from damage to[unreadable] the heart or its electrical system by ischemia, infarction, cardiac surgery, viruses, and assorted non-[unreadable] cardiac diseases. Our ability to identify which patients are at the highest risk of sudden death is poor,[unreadable] with ejection fraction being the only major clinical tool available for risk stratification. In addition,[unreadable] internal cardioverter-defibrillator (ICD) placement is the only effective therapy for high risk patients.[unreadable] Thus, the identification for novel tools to study arrhythmias in-vivo and stratify arrhythmic risk would[unreadable] represent a major advance to cardiovascular care.[unreadable] With the funding from the Pioneer Award, we will develop two novel and revolutionary techniques[unreadable] to image electrical activity in the intact heart in-vivo. First, we will adapt the most common clinical[unreadable] imaging technique, two-dimensional doppler echocardiography, to detect electrical activity in real time.[unreadable] Second, we will develop a modified autologous stem cell implant to detect adrenergic activity in the[unreadable] heart. These techniques will be developed in-vitro, tested in-vivo using animal models, and applied to[unreadable] humans when possible. If successful, both techniques will increase our understanding of arrhythmia[unreadable] mechanisms, improve risk stratification in patients at risk for sudden death, and guide therapeutic[unreadable] interventions.